This is the blog maintained by staff at Microsoft to provide general information, announcements and provide answers to Frequently Asked Questions (FAQs) related to daylight saving time (DST) and time zone (TZ) changes around the world.
* Important Notice

Q: Is there any reason not to use the /forcerebasesuppressallupdates switch with tzmove?

Q: Is there any reason not to recommend the use of the /forcerebasesuppressallupdates switch with tzmove? And what is the likely scenario why someone would get the error below?

Get the following error with the /FORCEREBASESUPPRESSALLUPDATES switch.

A: We do not recommend that customers use the /forcerebasesuppressallupdates switch with tzmove because ALL appointments in a users Calendar are updated regardless of who the organizer of the meeting is. In addition, no updates to meetings are sent out to any attendees.

The difficulty that is introduced due to these two factors is that every Calendar that has meetings in the organization has to have the /forcerebasesuppressallupdates command-line switch ran on their Calendar within a very short period of time. It’s difficult to coordinate this and it goes against how Outlook is designed to update meetings through meeting updates.

One example of the type of problem you could encounter would be if one user sent out a meeting series to 10 people and 5 of them already had the /forcerebasesuppressallupdates switch ran. When the remaining 5 have /forcerebasesuppressallupdates ran then those appointments will be at a different time than the other attendees and possibly even different than the organizer. In addition, meeting attendees that are outside of the Exchange organization would not get meeting updates so they would likely have to manually move those appointments or the appointments would be incorrect. There are other scenarios but you probably get the point.

As far as running the tool from the command-line. The syntax you are looking for is as follows with “User” being the mailbox owner:

tzmove /Q /FORCEREBASESUPPRESSALLUPDATES \\Mailbox - User\Calendar

Since you are using the /Q switch then you should look at the TZMOVE events in the Application Event log for information regarding how the tool executed.

Additional information:

/FORCEREBASESUPPRESSALLUPDATESThis option is known as "SuppressAll" in this article. SuppressAll is used to rebase all single-instance items if a time zone property does not exist. It is also used to rebase any recurring items that were created by using the DST 2006 rules. The rebase occurs regardless of who the organizer is. This mode will not send any updates for any reason.